Question

Identify the homoleptic complexes with odd number of d-electrons in the central metal:

• A. \([FeO_4]^{2-}\)
• B. \([Fe(CN)_6]^{3-}\)
• C. \([Fe(CN)_6]^{2-}\)
• D. \([CoCl_4]^{2-}\)

Hint:

To identify complexes with odd numbers of d-electrons, determine the oxidation state of the central metal and subtract the oxidation state from the total number of electrons in the neutral atom.

Answer 1

The Correct Option is A

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(A) \([FeO_4]^{2-}\): Iron in this complex is in the +2 oxidation state, with \( d^6 \) electrons. Since 6 is an even number, this complex does not meet the requirement for an odd number of d-electrons.
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(B) \([Fe(CN)_6]^{3-\):} Iron in this complex is in the +3 oxidation state, with \( d^5 \) electrons. This gives an odd number of d-electrons, so this is a homoleptic complex with odd d-electrons.
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(C) \([Fe(CN)_6]^{2-\):} Iron is in the +2 oxidation state with \( d^6 \) electrons. This complex has an even number of d-electrons.
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(D) \([CoCl_4]^{2-}\): Cobalt in this complex is in the +2 oxidation state, with \( d^7 \) electrons. This gives an odd number of d-electrons, so this is a homoleptic complex with odd d-electrons.
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(E) \([Co(H_2O)_6]^{3+\):} Cobalt in the +3 oxidation state has \( d^6 \) electrons, which is an even number.
Thus, the correct answer is

(1) (B) and (D) only.